OUTLINE FOR LABORATORY STUDY OF THE CHICK 343 



The kidneys and ureters. 



The testicles and the system of excretory ducts. 



The ovary and oviduct. 



PREPARATION OF STRUCTURES FOR STUDY 



It is hoped that the following suggestions will be helpful in the 

 laboratory work. 



. Directions for Dissecting Muscles; — ^The muscles that are brought 

 into great play in movements of the bird's limbs are dark carmine 

 in color, while those which are not brought greatly into use are pale 

 or white in color. 



The tendons are made up of white fibrous connective tissue, are 

 very dense, and pearly white in color. 



In securing a bird for dissection of muscles it is best to select one 

 in rather poor flesh, as the fat is anno)Tng. The bird may be 

 chloroformed or killed in a bell jar by aid of illuminating gas. 

 After the bird is dead pluck all the feathers and immerse it in a lo 

 per cent, solution of formaldehyde or of 80 per cent, alcohol. It is 

 best to puncture the abdominal wall so that the fluid may at once 

 flu the abdominal cavity and more readily gain access to the chest 

 cavity; and to puncture the skin at various points so that the liquid 

 may more quickly become disseminated among the muscular struc- 

 tures. Post-mortem changes quickly take place if these precautions 

 are not taken. The liquid surrounding the carcass should be at 

 least twice the quantity of the bulk of the carcass. 



The first dissection should be to lay bare the dermal muscles. 

 The dermal muscles are of two kinds, true dermal and dermo-osse- 

 ous. The dermal muscles have their origin and insertion in the skin, 

 and control the movements of the different groups of feathers. The 

 dermo-osseous have their origin on some part of the skeleton, and 

 insert to the integuments. 



The dermal muscles vary with the characteristics of the bird, we 

 do not find all the known dermal muscles in any one specimen. A 

 cock of the Cornish breed will show these muscles best developed. 

 Birds possess an enormous system of minute muscles divided up into 

 an infinite number of fasciculi, to act harmoniously upon the feather 

 quills and to agitate collectively the plumage. By the aid of a low- 

 power lens the action of the feather muscles in the large quill-butts 

 of the wing or the taU may be studied. 



The muscles may be studied in groups as outlined in the text. 



